Forty-four new heat flow values from panhandle Florida, southwestern Georgia, southern Alabama, Mississippi, and Louisiana range from 13 mW/m2 (0.3 HFU) (1 HFU=1 μcal cm-2 s-1=41.8 mW/m2) in Florida and Alabama to 88 mW/m2 (2.1 HFU) in northern Louisiana. In general, the values depict the eastern Gulf Coastal Plain as an area with low to normal continental heat flow that increases from east to west. Anomalously low heat flow (13-33 mW/m2) (0.3-0.8 HFU) characterizes northcentral Florida, southwestern Georgia, and southern Alabama, while in northern Louisiana, 13 measurement sites yield values ranging from 50 mW/m2 (1.2 HFU) to 88 mW/m2 (2.1 HFU). Distinctive disruptions in the temperature-depth profiles, attributed to convective effects within aquifers, are limited in magnitude and extent and do not alter the geothermal gradient computations. The region of relatively high heat flux in northern Louisiana is coincident with an area underlain by Cenozoic alkalic igneous rocks of the Monroe Uplift, and an abnormal concentration of radiogenic heat sources within that body is postulated as the cause of the thermal anomaly.